School of Materials Science & Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China.
Macromol Rapid Commun. 2024 May;45(9):e2300704. doi: 10.1002/marc.202300704. Epub 2024 Feb 17.
The isothermal melting behaviors of ultra-high molecular weight polyethylene (UHMWPE) with different entangled states (i.e., nascent and melt-crystallized samples) are studied. For two kinds of UHMWPE samples, the result shows that the relative content of survived crystals (X) exponentially decreases with time and reaches a constant value. It is suggested that such a melting behavior is related to the observed nonlinear growth of crystals induced by the kinetically rejected entanglements accumulated at the growth front. Additionally, the exponential decay of X with time provides a characteristic melting time (τ) for the melting process. Compared to the melt-crystallized UHMWPE, the τ value of nascent UHMWPE is generally longer even in a higher temperature range, which is mainly because the former has a larger entanglement density difference. Furthermore, these observations demonstrate that UHMWPEs with different entangled states have an analogous melting mechanism since they exhibit a similar melting activation energy (≈1300 kJ mol).
研究了具有不同缠结状态（即初生和熔体结晶样品）的超高分子量聚乙烯（UHMWPE）的等温熔融行为。对于两种 UHMWPE 样品，结果表明，幸存晶体的相对含量（X）随时间呈指数衰减，并达到一个恒定值。这表明这种熔融行为与观察到的由在生长前沿累积的动力学排斥缠结引起的晶体非线性生长有关。此外，X 随时间的指数衰减为熔融过程提供了一个特征熔融时间（τ）。与熔体结晶的 UHMWPE 相比，初生 UHMWPE 的 τ 值通常更长，即使在较高的温度范围内也是如此，这主要是因为前者的缠结密度差较大。此外，这些观察结果表明，具有不同缠结状态的 UHMWPE 具有类似的熔融机制，因为它们表现出相似的熔融活化能（≈1300kJ/mol）。
